I am trying to improve a search box on a website, at the moment you can search by keyword but doing this looks at every word entered, if possible I want it to search for all keywords in any order so that the results page shows the most relevant results.

Example:I search for "C4 envelope" and it returns 728 results with some results only having 'C4' in an others having 'envelope' in and I want it to only search for items containing both C4 and envelope.

Thank you for any help that you can offer.

Sorry for being so bad at explaining, here is my code for the search box: